1. Field of the Invention
This invention relates to a portable information terminal device such as cellular phone or PDA (personal digital assistant). More particularly, the present invention relates to a portable information terminal device having a camera feature.
2. Description of the Related Art
In recent years, portable information terminal devices such as cellular phones and PDAs that are provided with a built-in camera feature have been developed due to the availability of small and low power consumption image pickup devices, electronic devices having improved processing capabilities, large capacity memories and high speed and large capacity (broad band) communication lines. Such a built-in camera feature is normally realized by using a CMOS (complementary metal-oxide semiconductor) image sensor.
Since such a portable information terminal device can be put into a bag or a pocket and carried by the user, it may be provided with a flipper for preventing it from being unintentionally operated if the operation keys are accidentally turned or depressed. The flipper is closed to cover the operation keys when the device is stored or carried so that the keys cannot be turned or depressed by mistake. There are also many portable information terminal devices of the type that come in two parts. The two parts of such a terminal device are linked to each other by a hinge and adapted to be folded together. An LCD (liquid crystal display) is arranged on one of them, while operation keys are arranged on the other. Foldable devices are advantageous in that they are compact when folded, which reliably prevents operation errors, and the liquid crystal screen is relatively large and protected against damage.
Additionally, in recent years, many sophisticated multifunctional cellular phones can be utilized not only for telephone communications but also for viewing electronic mail (E-mail) and accessing Internet contents. The foldable type is advantageous for such cellular phones because they can be equipped with a large LCD that can display a large amount of information at one time. Therefore, the demand for foldable cellular phones is increasing.
Now, an increasing number of cellular phones are provided with a built-in small image pickup module and hence a camera feature.
Meanwhile, portable and foldable information terminal devices such as PDAs and hand-held PCs (personal computers) are becoming popular because they can be conveniently stored when they are carried by users and the liquid display screen is protected. Again, an LCD is arranged on one of the two parts, while operation keys are arranged on the other. An increasing number of such information terminal devices are also provided with a built-in small image pickup module and hence a camera feature.
Thus, there are a large number of portable information terminal devices that are flippable or foldable and are also provided with a built-in image pickup module.
On the other hand, the image pickup modules built-in to such portable information terminal devices are required to be compact and lightweight and hence are not provided with a zooming mechanism, unlike ordinary cameras. In other words, a single focal point lens is used. Therefore, the magnification, the view angle and other parameters of the lens are fixed to values that are suitable for snap shots and not adjustable because the built-in cameras of portable information terminal devices are believed to be normally used for snap shots. In short, the built-in cameras of portable devices provide only a limited use of obtaining snap shots (without zooming).
It may be possible to change the view angle by so-called digital zooming of partly enlarging the electrically picked up image and taking out the enlarged part. However, since the built-in camera of a small portable device needs to meet the requirements of compactness, lightweight and low power consumption, the number of pixels of the image pickup device cannot be so large. Thus, digital zooming can give rise to a problem of remarkably degrading the image quality.